1. Field of the Invention
This invention relates, in general, to a syrup evaporator apparatus having included therein a preheater for base fluid (sap) that is to be concentrated, and more particularly, a preheater that operates as a condenser to recover potable water from the evaporator exhaust effluent.
2. Discussion of the Art
The concentration of sugar-containing fluid in order to acquire a syrup is a well practiced art. Generally, evaporators of every type are used to manufacture maple sugar, sorghum and similar types of syrup or sugar products. In some of the modern day concentrator-evaporator apparata, preheating devices are used in order to pretreat the base fluid (sap) in anticipation of its introduction to the boiler (or evaporator) stages in the equipment. In the syrup producing industry, few seem to have concentrated on improving the preheating device, and perhaps less have attempted to recover any useful product from the vented effluent which is comprised almost entirely of steam. Quite matter-of-factly, any effluent more than a couple of feet above the boiling pan liquid surface comprises only steam.
Having a knowledge of these facts and an intention to improve the heat exchange characteristics of base fluid preheaters, as well as ameliorate what I perceive as waste of the unused steam effluent, I devised the instant invention to greatly enhance base fluid preheating while concurrently recovering, for the first time, potable water from the vented steam of almost any syrup evaporator.
After an exhaustive search in the literature available in the sugar and syrup making industry, as well as the patents available in the United States Patent and Trademark Office, I found only two references having any relevance to the instant invention. U.S. Pat. No. 4,819,615, issued to Richardson et al. in April 1989, discloses what the patentees term a piggy-back evaporator system. This comprises a sealably coupled box overlying a similar box-shaped sugar maple sap evaporator. An oblique condensate drain sheet extending the major length of the piggy-back evaporator funnels condensate from the bottom surface of the piggy-back apparatus back into the evaporator pan. Sap in the piggy-back pan is, more or less, preheated and introduced to the evaporator boiling pan. The steam vent, perched atop the hood of the evaporator is ordinary and otherwise unremarkable. Richardson et al. do not teach a preheater as a separable unit that is attachable to the stack or any stack which serves as a steam vent in the entire apparatus class known as concentrators/evaporartors.
The more relevant art discovered is found in the 1990 Sugaring Season Catalog of the G. H. Grimm Company of Rutland, Vt. The Grimm Company has, for years, been the leader in the maple syrup production industry and has recently begun to display a side-mounted preheater apparatus for use with its Lightning Evaporator.TM. syrup concentrator. The Grimm preheater uses recycled flue pan steam to heat cold sap by passing the sap through a two inch copper coil pipe before it is introduced to the regulator which controls the volume of sap introduced directly into the boiling pan. The Grimm Company employs a side-mounted unit to preclude condensed steam from dripping back into the flue pan, contra the Richardson et al. teaching. The Grimmy teaches that such a dripping back inevitably slows down the boiling process. Instead, in the Grimm preheater, a steady stream of hot water escapes out of the farside of the device; the water being clearly of a non-potable nature in that it is used according to the teachings of the Grimm Company for "clean-up chores". For all of its improvement to the art, however, the Grimm apparatus contains two obvious drawbacks in this preheater-condenser apparatus: first, the side mounting of the preheater places it immediately adjacent the boiling pan and thus makes it susceptible to spattering and foam overflow contamination of the condensed water that is used for cleaning chores; and second, the diameter of the copper coil pipes in the exchanger limit the surface area for heat transfer as well as the amount of contact area that would generate a greater amount of steam condensate for such chore work. Thus, the Grimm preheater-condenser produces a relatively low volume of contaminated condensate (contaminated with sap or other base fluid impurities) while it lacks optimum heat exchange efficiency because of the limited surface area available in such a heat exchange apparatus.
My invention, an improved preheater-condenser fulfills the need for a full-spectrum evaporator apparatus not quite achieved by Richardson et al., while greatly improving, especially by facilitating the production of potable water, the G. H. Grimm preheater-condenser.